The present invention generally relates to devices for hanging pipes and in particular for securing a run of plastic drain pipe, typically abs or pvc pipe, beneath structural elements of a building at a fixed grade for proper drainage.
When a building is constructed drain pipes must normally be plumbed from various locations within the building to an external drain line. The sections of pipe, typically ranging from 11/2" to 4" in diameter, are joined together by various types of fittings to create an extended run of pipe, the horizontal portions of which must be suspended from structural elements of the building, such as the floor joists. Also, to maintain proper drainage it is important that the pipe, throughout its run, have a suitable grade and that the pipe not be allowed to shift to a position that would eliminate the grade over any part of the pipes length. Also of concern is lateral shifting. The pipe needs to be held in a fixed position, yet loosely enough to accommodate natural expansion and contraction of the pipe.
Cast iron pipe, one time in widespread use, was typically suspended by means of "plumbers tape", a flexible metal strip which cradles the pipe and is nailed to overhead structural elements through pre-drilled holes in the tape. Because plastic pipe has substantially replaced the use of cast iron pipe, more rigid hanger devices have been devised to prevent the lighter and more flexible plastic pipe from "floating" as the pipe is subjected to the external or internal temperature changes. One such device is illustrated in U.S. Pat. No. 3,273,837, issued Sept. 20, 1966, to C. C. Wallert, et al., which discloses a pipe hanger that rigidly holds the plastic drain pipe in a fixed position. The Willert patent also discusses an additional general requirement for supporting plastic pipe, that of requiring more closely spaced support elements to avoid sagging.
However, the disadvantage with existing pipe hangers, such as disclosed in the Wallert patent, is that each pipe hanger is designed for a specific pipe diameter requiring a different size device for each change in pipe size. Moreover, it often occurs that a pipe needs to be held at a position where a pipe fitting is found. At such a position plastic pipe hangers produced for standard sized pipe diameters cannot be used.
The present invention provides an adjustable pipe hanger which, in one device, will accommodate most standard sized plastic pipes and which will securely hold a relatively small or relatively large pipe in a fixed vertical elevation as well as against undesirable lateral movement, while accommodating normally experienced pipe expansion and contraction. The pipe hanger of the invention can be designed to fit standard size pipe fittings in addition to standard size pipes, and can be installed easily and quickly. Moreover, the design of the invention is such that it adapts itself to inexpensive fabrication techniques, such as injection molding, and therefore can be made in large quatities relatively inexpensively.